The invention relates to a method for the manufacture of oval chain links out of round wire. A straight wire length, which perpendicularly crosses the longitudinal axis of a cylindrical bending mandrel having an annular groove surrounding this axis in a vertical plane to receive the wire length, is brought toward the mandrel at the level of the groove but spaced therefrom. The center of the wire length which forms the back of the link is moved into a recess in the mandrel at its entry side and in line with the groove therein. The wire length separated from the wire is bent into the groove outside of the mandrel recess until the longitudinal axis of the wire length follows the course of the groove; and to an apparatus for performing the method, having a bending mandrel, which has a recess on the wire delivery side of the mandrel to receive the outwardly concave curved back section of the unwelded chain link, the center of which recess if arranged opposite a holder for the length which can slide forward and back normally to the longitudinal axis of the mandrel; having two wire bending tools arranged symmetrically at the sides of the mandrel and holder, which tools can be moved on the side of the mandrel opposite the holder from the holder side of the mandrel toward the two ends of the wire end or piece positioned between the mandrel and the holder; and having a device for positioning the wire length between the mandrel and holder, which has a wire feed sleeve which is stationary or can be moved with one of the two tools, and has a stop element for the emerging free end of the wire length, said stop element lying axially opposite said wire feed sleeve, whereby the wire bending tools can be moved out beyond the mandrel and back perpendicularly to the wire feed direction and parallel to the direction of movement of the holder toward the two ends of the positioned wire length.
A device of the aforementioned type is described in German Patent No. DE-AS 1 527 505, where a method of the type described above can be performed. Wire length, or pins, of a given equal lenth are worked. The pins are first cut at the pin length discontinuously from a wire end that is pushed through the feed sleeve (knife sleeve 11) until it abuts the plate-like stop element (stop plate 21), said cutting occurs by means of a blade (12) in the plane of the frontal surface (28) of the feed sleeve (11) facing the parallel stop surface (29) of the stop plate (21), which blade is parallel to the two bending tools (bending steels 14) and is moved together therewith. Correspondin to the blade (12) on the feed sleeve (11) associated with the pin end to be cut is a sliding steel (24) on the stop plate (21) which is associated with the free pin ends and is identical with the respective leading free end of the wire end, which stop plate (21) is aligned with and simultaneously can be moved along with the two bending tools (14) of the stop surface (29), so that the frontal surface (18) of the free pin end, which is a cutting surface, while the changing of the straight pin into a wire piece with complete back bending of the produced chain link, which is effected exclusively by means of the holder (27) pushing against the bending mandrel (16), is not distorted. The changing of the bird wing-like wire length into a C-shaped wire length then takes place by means of the two bending tools (14), which are followed by the ineffective blade (12) and the sliding steel (24). Subsequently, two additional bending tools (bending steel 30) which can be moved together and apart in the plane on which the mandrel axis lies vertically, effect a changing of the C-shape of the wire length into an O-shape, which, of course, exhibits the back rounding of the now finished unwelded chain links. According to FIG. 2 of German Patent No. DE-AS 1 527 505, the lateral distance of the pin from the mandrel (16) is just one times the wire diameter; which corresponds to a vertical spacing of the longitudinal axis of the feed sleeve (11) from the cord lying tangent to the mandrel (16) of just one and one half times the wire diameter. This spacing would not be met with the observation that could be led back to the fact that in the known method the preliminary and finish bending take place in one and the same bending station, so that in any case one must wait for the completion of each unwelded chain link before the next pin receives the back bending in a first step of its shaping into the O-shape with a back rounding.
It appears disadvantageous to the known apparatus, the operational method of which corresponds to the method performed therewith, that as the wire end is moved into the single (or first) bending station one must always wait until the bent wire length has obtained its open O-shape (or closed C-shape), because until then the back of the portion of the unwelded chain link to be produced at least partially occupies the space between the mandrel and the holder, so that as it moves forward, the wire end would be prevented from reaching the stop element by this back portion. Consequently, the machine production of unwelded chain links is not as high as it could be, if this mentioned limitation did not exist.